Thermal responsive circuit controller



Nov. 10, 1925- 1,560,932

J. EATON THERMAL BESPONSIVE CIRCUIT CONTROLLER Filed Aug. 27, 1923 2Sheets-Sheet i Fig. 1. Q

Nov. 10, 1925. 1,560,932

J. EATON THERMAL RESPONSIVE CIRCUIT CONTROLLER Filed Aug. 27, 1923 2Sheets-Sheet 2 Fig. 4.

iii 2 b a;

17 24 6 29 2' F i Fig.5.

Im/ehtor i Patented Nov. 10, 1925.

UNITED STATES 'JOHN EATON, OI SCHENECTADY, NEW YORK, ASSIGNOB '10GENERAL ELECTRIC OOH- nmr, A oonrom'rron or saw your.

THERMAL BESPONBIVE CIRCUIT CONTROLLER.

Application am: n w 27, 102:. Serial in. 659,420. I

'1 0 all whom it may concern Be it known that 1, JOHN EATON, a subjectof the British Empire, residing at Schenectady, in the county ofSchenectady, State of New York, have invented certain new and usefulImprovements in Thermal Responsive Circuit Controllers, of which thefollowing is a specification.

My invention relates to improvements in thermal res onsive circuitcontrollers, and one of the olijects of the invention is to provide anarrangement whereby when the circuit controller has automaticallyoperated, after an interval of time it will be automatically reset foranother operation.

Another object of the invention is to provide an arrangement whereby theresetting is accomplished by a temporary energization of the resettingmeans.

A further object of the invention is the provision of an arrangementwhich is simple in construction and reliable in operation, and onewhereby the controlled circuit is automatically and positively openedand reclosed depending on the thermal condition of a'thermal responsivecontrolling element.

Another object of the invention is to pro vide a circuit controllerwhich operates in response to the heating effect of a thermal responsiveelement to protect a controlled circuit from conditions caused byoverloads of a minor nature which persist for time intervals regarded asunsafe, and in case the overload is of a greater value, the circuitcontroller will operate instantly regardless of the thermal condition ofthe thermal responsive element.

A still further object of the invention is to provide a thermalresponsive circuit controller of the character indicated which willautomatically operate a predetermined number of times and then have thefurther automatic operation temporarily arrested. Such protection isdesirable for certain applications in which the repeated operation ofthe controller would indicate that there is a dangerous conditionpresent in the controlled circuit which should be called to theattention of the operator.

These and other objects of the invention, as will be apparent to thoseskilled in the art or as will be pointed out particularly hereinafter,are attained in the thermal responsive circuit controller illustrated inthe accompanying drawings, in which Figure 1 is a simplified motorcontrol diagram showmg a controller in accordance with the inventlon;Fig. 2 is a detail of the controller with the parts of the same in theirrespectwo positions after the thermal responsive element has operated toopen the controlled clrcuit; Fig. 3 is a similar detail showing theparts in their respective positions when the thermal responsive elementhas cooled and closed the circuit of the resetting electro-magnetpreparatory to closing the con trolled circuit; Fig. 4 is a verysimplified motor control diagram in which the circuit controller isprovided with means forinstant-ly interrupting the controlled circuit inresponse to overloads in excess of the ordinary overloads for which thethermal responsive device gives protection; and Fig. 5 is a detail of amodification of the controller to provide for automatically arrestingthe automatic operation of the controller after a predetermined numberof operations.

Referring to the drawings, the thermal responsive circuit controllercomprises a switch member 10 for controlling the circuit of the linecontactor 11 included in the armature circuit of an electric motor 12,the device which I have selected for illustration as a device to beprotected by the controller. The switch member 10 is under the controlof the thermal responsive element 13, which is indicated as of thebimetallic thermostatic type, and which is arranged to be heated in anysuitable manner, as by means of the heating coil 14 W0 (1 about andinsulated from the bi-meta lic strip of the thermostat. The heating coilof the thermal responsive element may be connected in the circuit of themotor 12 so as to be heated in accordance with the current taken by themotor. The thermal responsive element serves as a latch to hold theswitch member 10 in the closed position, and one end of the element issecurely held and the other end is arranged to make a sliding andabutting engagement with the pivotally mounted switch member 15 forcontrolling the electromagnet 16 which serves as the resetting means forautomatically reclosing the switch member 10 after the thermalresponsive element has operated to release the same. The switch member15 is pivotally mounted on one end of the armature 17 of theelectromagnet, and the sponsive element.

switch member 15 is biased to the position shown in thedrawing by thespring 18.

The arrangement in general'is such that when the thermal responsiveelement or latch 13 is heated to a predetermined degree, the end of thelatch will slide free from the post 19 and thus release the arma ture 17to automatically move to the unattracted position due to the bias of thespring 20, and thus carry the switch member 10 to the open position.When the thermostatic latch has cooled, the switch member 15 is movedcounter-clockwise about its pivotal support against the action of thespring 18 so as to cause this switch member to move to the closedposition and thus temporarily energize the resetting electromagnet 16.The energization of the electromagnet 16 causes the armature 17 to beattracted so as to opcrate the switch member 10 to the closed positionand bring the post 19 into abutting engagement with the end of thethermostatic latch so as to place the switch member 10 again under thecontrol of the thermal re- When the armature 17 is moved to theattracted position, the switch member 15 is permitted to interrupt thecircuit of the resetting electromagnet so as to place the switch member10 entirely under the control of the thermal condition of the element 13and to have the resetting electromagnet deenergized as long as theconditions in the controlled circuit are normal.

As thus constructed and arranged, and

' with the various parts in their respective positions indicated in Fig.1, the operation of my invention is as follows: In order to close thecircuit for the motor 12, the pilot switch 21 will first be closed so asto energize the line contactor 11, the circuit being through themagnetic structure of the resetting electromagnet 16, the switch member10, switch 21, and the winding of contactor 11. Contactor 11 is thusenergized to close and connect the motor to the source of Sn plyindicated. The heating coil 14 of the t hermal responsive element is nowconnected in the motor circuit so that this element is heated inaccordance with the thermal conditions of the motor circuit. In case anoverload on the motor should persist for a predetermined length of time,the lower end of the thermostatic latch 13 will flex to the right andslide out of abutting engagement with the post 19. The armature 17 andthe switch member 10 will thus be released to move counter-clockwiseabout the pivotal support cool. The cooling of this late the heatingcoil 14 thereby deener gi zed so that the thermostatic latch is ermittedto the lower end thereof to move clockwise so as to press against theright-hand side of the post 19 and thus move the switch member 15counterclockwise into engagement with the stationary contact 22 againstthe action of the spring 18. The parts will now be in their respectivepositions indicated in Fig. 3. The closing of the switch member 15 willenergize the electromagnet 16, through a circuit including the magneticstructure of the electromagnet 16, so as to attract the armature 17 andthus automatically close the circuit for the contactor '11 through theswitch member 10. The post19 is moved so as to come into abutting engagement with the end of the thermostatic latch, and the armature 17 and theswitch member 10 are thus retained in their respective positionsindicated in Fig. 1. The switch member 15 is permitted to interrupt thecircuit for the winding of the resetting electromagnet 16 after thereclosing operation has been effected. This is due to the fact that theswitch member 15 is biased to the position indicated in Fig. 1 by theaction of the spring 18. The device is now ready for another operationto control the circuit of the electric motor to protect from conditionscaused by overheating.

The arrangement of Fig. 4 is essentially the same as that indicated inFig. 1, and the operation is also essentially the same. In order toprotect the motor from instantaneous overloads of a. higher value thanthe 'overloads for which the thermal responsive element is provided togive protection, the overload electromagnet 23 is included in thecircuit of the electric motor. This overload electromagnet serves toattract an armature 24 secured to the switch member 15 so as to slidethe post 19 out of abutting engagement with the end of the thermostaticlatch 13 and thus efiect the opening of the switch member 10 in the samemanner as if the thermostatic latch hadoperated to effect the opening ofthe controlled circuit. The automatic reclosing of the controlledcircuit will be eifected in the same manner as previously described inconnection with Fig. 1.

In Fig. 5 I have shown a detail of a modification in which the circuitcontroller is permitted to automatically operate a predetermined numberof times and then have its automatic operation arrested. Theelectromagnet 16 is connected to be energized through the conductingsegment 25 of a rotating member which is ratcheted step by step in theclockwise direction by the catch 26 connected to the switch member 15.The switch member 15 will complete a circuit for the winding of theresetting electromagnet through the conductor segment 25 and the willcause contact linger 27 until the segment :25 has been ratcheted to theposition at which the insulating segment 28 makes engagement with thecontactfinger 27. It will thus be impossible for the switch member 15 tocom plete the ('ll'tlllt for the resetting electromagnet so that theautomatic reelosing ot the switch member 10 will not be eti'ccted. Theattention of the operator is thus called to the fact that there is somecondition present in the motor circuit which requires his attentionbefore again closing the motor circuit. After this condition isremedied, the operator may eli'ect the closing of the controlled circuitby closing the push button '29 so as to energize the resettingelectromagnet independently of the switch member 15. 'hen the controlleragain operates to open the controlled circuit, the catch 26 will operateto rotate the insulating segment 28 out of engagement with the contactfinger :27 and the contact carried by the end of the switch member 15 sothat the controlled circuit will be automatically reclosed in the mannerpreviously described.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment.thereof, but I desire to have it understood that the apparatus shown isonly illustrative and that the invention may be carried out by othermeans.

What I claim as new and desire to sekure by Letters Patent of the UnitedStates, is:

l. A thermal responsive circuit controller comprising a switch membermovable to and from a closed position, a thermal responsive controllingelement arranged to hold the switch member in one position while thethermal condition of the element is substantially normal and to etiectthe return of the witch member to the other position in response to theheating of the element beyond a predetermined degree, and meanscontrolled by said element temporarily during the cooling thereof foroperating the switch member to the position in which the member is heldby the said element.

2. A thermal responsive circuit controller -on'iprising a switch membermovable to and from a closed position, electroresponsive means foroperating the same from one position to the other, a thermal responsivecontrolling element arranged to hold the switch member in the operatedposition while the thermal condition of the element is substantiallynormal and to effect the return of the switch member in response to theheating of the element beyond a predetermined degree, and meanscontrolled by said element temporarily during the cooling thereof forcontrolling the energization of said electromagnet.

3. A thermal responsive circuit controller comprising a switch memberbiased to one position, a thermal responsive cmiti-ollilig element forholding the same in a second position, and electroresponsive meanstemporarily energized responsively to the th rmal condition of saidelement for operating the said switch member to the second position a iter the said element has released the switch member to return to thefirst position.

l. A thermal responsive circuit controller comprising a switch memberbiased to one position, an electromagnet for operating the switch memberto a second position, and a thermal responsive controlling element forholding the said switch member in the second position while the thermalconditions of the controlled circuit are substantially normal, the saidelement arranged to release the said switch member to move to the firstposition when the thermal conditions of the controlled circuit becomeabnormal, and switch mechanism and tonnections'whereby the said elementtemporarily controls the energization of the said electromagnet toreturn the said switch member to the second position an interval of timeafter the element has released the switch member.

5. A thermal responsive circuit controller comprising a switch memberbiased to the open position, a thermostatic latch arranged to hold theswitch member in the closed position, and arranged to flex when heatedand release the switch member to move to the open position, andeleetroresponsive means energized responsively to the cooling of thesaid thermostat for returning the said switch member to the closedposition.

6. A thermal responsive circuit controller comprising a switch memberbiased to one position, electroresponsive means for operating the switchmember to a second position, a thermal responsive controlling elementfor holding the switch member in the second position, and a switchoperated responsivelv to the thermal condition of said elementforcontrolling the said electroresponsive means to place the said switchmember under the control of said thermalresponsive element.

7. A thermal responsive circuit controller comprising a switch memberbiased to one position normally deenergized, electroresponsive meanswhich when energized operates the switch member to a second position, athermal responsive element connected to be heated when the said switchmember is in the second position for holding the switch member in thesecond position, and arranged when heated to a predetermined degree torelease the switch member to move to the first position, and a switchoperated by the said element during the cooling thereof for temporarilyenergizing the said electroresponsive means, to operate, the switchmember to the second position.

S. A thermal responsive circuit controller, I

comprising a switch member biased to the open position, a normallydecnergized electromagnet having a magnetic movable member Connected tothe switch member for operating the same to the closed position, athermal responsive element arranged to hold the switch member in theclosed position with during the cooling thereof for temporarilyenergizing the said electromagnet to operate the first switch member tothe closed position.

9. A thermal responsive circuit controller comprising a switch member, anormally deenergized eleetromagnet having a pivotally mounted armaturebiased to the unattracted position and connected to the switch memberfor operating the same to the closed position when energized, athermostatic latch arranged to hold the switch member in the closedposition and the said armature in the attracted position with theelectromagnet deenergized while the thermal condition of the saidelement is substantially normal and to release the switch member toreturn to theopen position and the said armature to return to theunattracted position when the element is heated to a predetermineddegree, and a second switch member pivotally mounted on the saidarmature, biased to the open position, and connected to be operated tothe closed position by the said element during the coolin thereof fortemporarily energlzing the sai electromagnet to operate the first switchmember to the closed position.

10. A thermal responsive circuit controller comprising a switch memberbias to one position, a thermal responsive element arranged to be heatedin accordance with the current in the circuit to be controlled forholding the switch member in the second position, and arranged torelease the switch member when heated to a predetermined degree,electroresponsive means energized responsively to the thermal conditionof the element for operating the switch member to the second positionafter the switch member is released to move to the first position, andan overload electromagnet for releasing the switch member independentlyof theoperation of the said element.

11. A thermal responsive circuit controller comprising a switch membermovable to and from a closed position, a thermal responsive elementarranged to hold'the switch member in one position while the thermalcondition of the element is substantially normal and to effect the.return of the switch member to the other position in response to theheating of the element beyond a predetermined degree, and meanscontrolled b the cooling of said element for automatically operating theswitch member a predetermined number of times to the position in whichthe men'iber is held by the element and then arresting the furtherautomai ic operation of the switch member.

12. A thermal responsive circuit controller comprising a switch membermovable to and from a closed position, a thermal responsive elementarranged to hold the switch member in one position while the thermalcondition of the element is substantially normal and to eifect thereturn of the switch member to the other position in response to theheating of the element beyond a predetermined degree, means controlledby the cooling of said element for automatically operating the switchmember to the position in which the member is held by the said element,and means controlled by the first mentioned means for limiting thenumber of times the first mentioned means is effective to automaticallyoperate the said switch member to the said second position.

13. A thermal responsive circuit controller comprising a switch memberbiased to one position, a thermal responsive element arranged to beheated in accordance with the current in the circuit to be controlledfor holding the switch member in the second position, and arranged torelease the switch member when heated to a predetermined de gree,electroresponsive means energized responsively to the thermal conditionof the element for operating the switch member to the second positionafter the switch member is released to move to the first position, andmeans controlled by the said electromagnet for limiting the mmiber oftimes the electromagnet is eifeetive to automatically operate the saidswitch member to the said secondposition.

In witness whereof, I have hereunto set my hand this 24th day of August,1923.

JOHN EATON.

